Cognitive impairment is a common adverse effect of HIV infection that can progress to dementia. ARVs are the only current therapy, but treatment response is frequently unsatisfactory, short lived, or the agents are poorly tolerated in doses adequate for central nervous system (CNS) penetration. An adjunctive therapy that interferes with the cascade of events triggered by the virus is likely to play an important role. Oral selegiline is an approved and marketed drug for the symptomatic treatment of Parkinson's disease. Studies suggest that selegiline has a neuroprotective effect and that it may exert a "rescue effect" on dying and injured neurons. This study proposes to use transdermal selegiline, which may deliver a greater dose level than oral administration, in the treatment of HIV-associated cognitive impairment.